Flow-through propeller

ABSTRACT

A MARINE PROPELLER ASSEMBLY OF THE EXHAUST FLOWTHROUGH TYPE, HAVING ANNULAR EXHAUST-FLOW-ALTERING PROTRUSION MEANS EXTENDING RADIALLY INTO THE FLOW THROUGH EXHAUST PASSAGE, CREATING A CENTURI TYPE STRUCTURE, AND HAVING A SPECIALLY TAPERED TERMINAL DISCHARGE PORTION, IMPROVING PERFORMANCE.

United States Patent 01 3,567,334 Patented Mar. 2, 1971 free 3,567,334 FLOW-THROUGH PROPELLER Eldon L. Lorenz, Grand Rapids, Mich., assignor to Michigan Wheel Company, Grand Rapids, Mich. Filed Sept. 9, 1968, Ser. No. 758,524 Int. Cl. B63h 1/18, 21/26 U.S. Cl. 416-93 1 Claim ABSTRACT OF THE DISCLOSURE A marine propeller assembly of the exhaust flowthrough type, having annular exhaust-flow-altering protrusion means extending radially into the flow through exhaust passage, creating a venturi type structure, and having a specially tapered terminal discharge portion, improving performance.

BACKGROUND OF THE INVENTION This invention relates to a marine propeller assembly, and more particularly to one of the exhaust flow-through type.

Propeller assemblies having exhaust flow through the hub have been offered in various forms heretofore. Yet, there has been a constant search in efforts to improve the performance characteristics of these units, without significantly increasing the cost thereof.

SUMMARY OF THE INVENTION It is the primary object of this invention to provide a unique propeller assembly of the exhaust flow-through type, having improved performance characteristics, yet without significant cost increase.

The novel assembly employs special venturi structure in the exhaust passage, such have been discovered to obtain improved performance characteristics. This is preferably used in combination with a special angle taper of the terminal portion of the inner periphery of the outer sleeve of the assembly.

These and other objects, advantages, and features will become apparent upon studying the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational, fragmentary, sectional view of the underwater structure incorporating a propeller assembly of this invention;

FIG. 2 is a rear elevational view of the hub assembly in the central portion of the propeller assembly in FIG. 1, showing the plane II on which the section in FIG. 1 is taken;

FIG. 3 is an enlarged, fragmentary, partially sectioned view of an alternate form of the terminal portion of the outer sleeve of the assembly in FIG. 1;

FIG. 4 is a sectional side elevational view of a third embodiment of the novel structure; and

FIG. 5 is a sectional side elevational view of a fourth embodiment of the novel hub structure.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now specifically to the drawings, the complete underwater assembly illustrated in FIG. 1 includes the depending support casing 12 protruding downwardly from the power plant and drive assembly (not shown) of a typical marine outboard drive structure, to which is attached the propeller assembly 14.

Propeller assembly 14 is supported by and driven through structure 12, with the drive connection including the generally vertical, rotational drive shaft 16 mounted in suitable needle bearings 18 or the like Within a central enclosure 20. Enclosure 20 extends around this shaft within and spaced from outer casing 12 to define an annular exhaust flow passage 22. Shaft 16 has a beveltype spur gear 24 mounted on the lower end thereof, intermeshing with a bevel-type spur gear 26 mounted on generally horizontal shaft 28. Shaft 28 has its forward end mounted in bearing 30 in support 12, its central portion mounted in bearing 32, and a splined rear end 34 to drive the propeller. Mounted on splined end 34 is the inner annular sleeve 36 of propeller assembly 14, with retaining nut 38 threadably engaged on integral threaded stud 40 of shaft 28.

Bearing 32 is mounted in annular support 44 secured in structure 12 by a suitable threaded annular nut 46. Support 44 also retains ball bearing 48 around the sleeve of spur gear 26. Suitable packing 50 is employed around shaft 28 where the forward end of annular sleeve 36 abuts the drive connection shaft subassembly. Central sleeve 36 may include an inner resilient shock absorbing drive component 54 of rubber or the like.

Extending peripherally around central sleeve 36 is an outer sleeve 60 having an inner periphery spaced substantially radially outwardly from the outer periphery of central sleeve 36 to define an annular exhaust flowthrough passage portion 62 therebetween, to communicate with vertical passage 22. Outer sleeve 60 is also mounted on central sleeve 36 by a plurality, here three (FIG. 2), radially extending struts 64 which project through the annular exhaust passage portion '62.

Outer sleeve 60 also protrudes rearwardly of the central sleeve a considerable amount to form a second exhaust flow-through passage portion 66 that is generally cylindrical in configuration, and is communicant with annular portion 62, to form a continuous passage through the hub structure.

Special, annular, exhaust flow altering, protrussion means 61 extend radially into the passage in a manner and of a configuration to create a venturi-type structure which improves the performance characteristics of the propeller assembly. In the first form of the invention illustrated in FIG. 1, this annular protrusion projects radially inwardly from the inner periphery of outer sleeve 60 into the generally cylindrical exhaust flow-through passage 66 near the rear terminal portion of the passage and outer sleeve.

Preferably, as illustrated in FIG. 3, the structure includes a special taper in the rear portion of the modified outer sleeve 60a. The protrusion 61a tapers with a radially outwardly sloped inner periphery of the outer sleeve, so that surface 69 is at a small acute angle to the hub centerline, e.g. about 25. The very terminal edge 70 moreover, has a taper at a large acute angle to the hub centerline, specifically about Thus the combination preferably includes the annular protrusion 61a, tapered terminal portion 69 at a small acute angle, and tapered terminal edge 70 at a large acute angle with respect to the centerline of the hub assembly. This combination is particularly effective in improving the operational characteristics of the structure.

Alternate embodiments of the structure are illustrated in FIGS. 4 and 5. More specifically, the annular protrusion 61b of FIG. 4 extends radially outwardly of the outer periphery of inner sleeve 3612 into the annular flow passage portion 62b between central sleeve 36b and outer sleeve 6017.

In the structure in FIG. 5, annular protrusion 610 projects radially inwardly from the modified outer sleeve 600 into the annular passage portion 620. If desired, supplemental annular protrusion 61b can also project radially outwardly into the annular passage 62c from the outer periphery of inner sleeve 36c. The terminal portion of outer sleeve 600 has a generally cylindrical outer periphery, has a radially outwardly sloped terminal portion 69con its inner periphery at a small acute angle of about 10, and has a terminal edge 70c sloping radially outwardly fromthe inner periphery at a large acute angle of about 75 Operational testing of the novel structure has shown substantially improved performance to result from the unique assembly, although applicant does not have a scientific explanation of this. It is conceivable that the structure may be modified in other various minor manners without departing from the concept. Claim is made to the invention as set forth in the attached claim.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A marine propeller assembly of the exhaust flowthrough type, comprising: a central mount and drive connection sleeve; an outer unitary, elongated, cylindrical sleeve around said central sleeve, spaced from said central sleeve to define an annular exhaust flow passage portion therebetween, mounted on said central sleeve by radial struts in said annular passage portion, and extending substantially beyond said central sleeve to define a generally hollow and unobstructed cylindrical exhaust flow passage portion cornmunicant with said annular portion to collectively form a continuous passage; and annular exhaust-floW-altering protrusion means extending radially into said passage, said outer sleeve having a rear terminal portion with its inner surface only tapered radially outwardly at an acute angle, all in a manner and of a configuration to create a venturi-type structure.

References Cited UNITED STATES PATENTS 2,948 252 8/1960 Alexander i70--135.71UX

3,246,698 4/1966 Kiekhaefer 170l66 3,279,415 10/1966 Kiekhaefer 170-135.71UX

3,310,022 3/1967 Kollman 170135.71UX

3,434,447 3/ 1969 Christensen et a1.

EVERETTE A. POWELL, 111., Primary Examiner 

